This invention relates generally to reciprocating devices, and more particularly to a reciprocating device in which a reciprocating member alternately and selectively engages with either the forward (going up) side or the backward (going down) side of an endless member such as an endless chain or belt which is running in one direction, thereby being reciprocated.
Conventionally, in an automatic spray-coating painting apparatus used in a factory assembly line, for example, the spray-coating device is attached to a reciprocating device. A typical example of this is one in which two opposing sprocket wheels are joined by an endless chain, and the reciprocation of the reciprocating member is achieved by the movements of the chain.
This known reciprocating device has a disadvantage in which the reciprocating member reciprocates over the full distance between the two sprocket wheels, regardless of the size of the object to be painted. Accordingly, the reciprocating member can not reciprocate in only the desired range required for the painting process. Since the reciprocating range of the reciprocating member cannot be adjusted, and the reciprocating member undergoes unnecessary movements, it resulted in the degradation of the operation efficiency of the process.
An alternative method of providing reciprocation of the spray-coating device according to the size of the object to be painted, is to enable the chain to be driven in both directions.
However, this requires a bi-rotational motor, resulting in high cost and complication of the device construction, in addition, device of this type incorporates a plurality of guide posts to guide the reciprocating member.
Consequently, it has a disadvantage in that the guide posts have to be set up parallel to each other, which is difficult to achieve.